There have been approximately 5 million confirmed cases of Covid-19 around the world. I’m one of them.

In March, my partner, a sheriff’s deputy and first responder in New Hampshire, tested positive for the disease. A few weeks later, so did I. Our symptoms varied, and his were more severe than mine. We both feel fortunate to have recovered. But, like millions of others who have done so, we’ve been left with a burning question: Now what?

Are we now immune from future infection? And, if so, for how long?

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Serology testing — otherwise known as antibody testing — can indicate whether someone is producing an immune response to the virus. And in recent weeks antibody testing has become more widely available in the United States, including a test from Quest Diagnostics, which allows consumers to order it directly online before being directed to a local lab.

So a couple of weeks ago, I took it, eager to finally have some clarity on my own health. What I learned gave me some peace of mind, but also underlined how many questions the science still can’t answer yet. 

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The process of getting tested was quick and simple. I went online, ordered a test, and made a same-day appointment at a lab. All it took was a small blood draw and by 3 a.m. the next morning my results were waiting in my inbox. (Others have reported getting results has taken much longer.)

Here they are:

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The results were clearly intended to be straightforward enough. But for a layperson such as myself — and I’m sure for others like me — the results were also confusing. Clearly I was producing antibodies, which was a good thing. But to what end? 

I contacted Quest for answers and was put in touch with Andrew Abraham, a physician who works for PWN Health, a national clinician network company that partners with Quest to provide assistance to clients.

Abraham was patient with my questions, and explained that when people get sick with an infection they actually produce two kinds of antibodies, IgM and IgG. The IgM antibodies are the first, fast-acting antibodies that work to fight off a virus, but they don’t stick around. They do, however, stay around long enough for your body to then create IgG antibodies, which stay with you much longer depending on the virus it’s protecting you from. 

When a new pathogen causes illness, the immune system creates memories, so its cells can target and kill the invader if it ever comes back again. Here’s how a person becomes develops immunity. Hyacinth Empinado/STAT

The reality is that, as a result, my body would likely fight off the virus if I encountered it again. But Abraham cautioned that I’m not invincible. At this point, science has no way of telling how long my IgG antibodies will remain with me.

“We want to make sure the consumer understands that there are some limitations around the test and that unfortunately, at this point, we can’t see it as a passport to immunity as was once kind of widely heralded as the panacea to Covid,” PWN’s chief medical officer, Doug Elwood, told me.

At the moment, PWN only validates two tests: the one from Quest, and another from LabCorp. What made them so special? 

Both tests meet the company’s criteria for specificity and sensitivity, crucial terms of understanding antibody testing.

When assessing the test’s accuracy, “sensitivity” refers to the ability of the test to detect antibodies to SARS-CoV-2. A test with a low sensitivity will produce more false negatives, telling people they haven’t been infected with the virus when they have been. “Specificity” refers to a test’s ability to return a negative result when people really haven’t been infected with the virus. A test with a low specificity will return more false positives, telling people they have been infected when they really haven’t.

Quest’s test has a sensitivity rate of over 90% and specificity 99% to 100%. 

That leaves open the possibility that some very small number of people’s results will be false-positives or false negatives. And it means that taking the tests do come with some risks, like virtually any test.

When I asked Quest’s chief medical officer, Jay Wohlgemuth, who the company believes should be getting a serology test, he said the ideal candidates are people who believe they may have been previously exposed to the virus but are no longer sick. “For anyone who is sick, they should be getting a PCR test,” Wohlgemuth said, referring to the nasal swabs that help diagnose active infections.

The population of candidates for the test is likely sizable. Given a monthslong shortage of Covid-19 tests in much of the country, there are countless people who think they may have had the disease — but aren’t sure. And some people may have had PCR tests and come up with false negatives.

My own experience was a mixed bag. I wanted to find comfort in being told that my restlessness over Covid-19 was for naught — and that my partner and I aren’t going to be infected again. I wanted that peace of mind that, even with a mask on, I’m never going to be at risk of infecting others when I’m going to the store or walking my dogs — if I get sick again. 

The reality is that science can’t yet offer me, or any of us, those assurances. 

I’m not an unabashed optimist. I realize there is still so much that we don’t know about Covid-19. But having answers, even fleeting ones, has allayed some of my concerns for now. 

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